The parents of Boston marathon bombing suspects Dzhokhar and Tamerlan Tsarnaev have claimed that their sons have been set up.

Speaking to TR America, their mother Zubeidat Tsarnaeva said her elder son Tamerlan had been interviewed by the FBI after becoming an increasingly devout Muslim, and the agency then monitored him.

"My two sons are really innocent and I know neither of them have never, never talked about what they're saying about them now," she said.

"I know my son never spoke about those things. I am a mother, I raised them.

"My oldest son used to tell me everything. He used to call me and ask me, 'How are you mama?' Both of them, 'Mama we love you, mama how are you, we miss you.'

"It is impossible, impossible for them, for both of them to do such things."

She said that her sons did not keep secrets from her.

"This is a set-up; my son would never ever carry out such terror attack," she said.

"FBI knew everything what my son was doing, told me he was serious leader, that they were afraid of him.

"He was controlled by the FBI for three to five years. They knew what my son was doing. They knew actions, and what sites on the internet he was going."

Tsarnaeva went on to emphasise that Dzhokhar was raised in the US and insisted that "no one ever talked about terror" in their house.

The FBI has confirmed that it interviewed Tamerlan in 2011, and claimed that no incriminating evidence on extremists links was uncovered.

The agency said that the interview was made at the request of a foreign government, though it did not say which government.

On Friday US president Barack Obama spoke to Russian leader Vladimir Putin by telephone, and thanked the Russians for their help in counter-terrorism operations.

The surviving suspect, 19-year-old Dzhokhar Tsarnaev, is currently in custody after being found hiding in a boat, wounded, in a garden in the Watertown area of Boston on Friday night. His brother was killed in a gun battle with police in the early hours of Friday.

Their father, Anzor Tsarnaev, who lives in the Russian town of Makhachkala, also refused to believe that his sons could be responsible for the bombing, which killed three people and injured 176.

"They never could have done this. Never, ever, ever!" he said.

He said they had been set up, said that if Dzhokhar were killed by police he would see it as proof of a conspiracy.

"If they killed him, then all hell would break loose," he told ABC News.

"If they kill my second child, I will know that it is an inside job, a hit job. The police are to blame."

He said that he had spoken to his sons two days after the bombing, when they told him: "Everything is good, Daddy. Everything is very good."

He went on to say that they were good kids with "big dreams".

"I am very depressed. How am I going to live? Never I think in my mind this happen. My sons hate people who do bombs, they hate terrorists. Why they kill my son? And where is my other son? They have time to catch my other son, not kill," he said, shortly before Dzhokhar's arrest.